1. Field of the Invention
The present invention relates to a light-emitting diode and, more particularly, to a light-emitting diode used for decoration.
2. Description of the Related Art
FIG. 1 is a schematic view of a light-emitting diode according to the related art. Arrows in FIG. 1 designate the direction of emitted light. Conventionally, a light-emitting diode is primarily used as an indicator in an electronic appliance, etc. Therefore, a light-emitting diode according to the related art exhibits very sharp front directionality since there is a requirement to ensure visibility from the front (from top of FIG. 1).
Recently, light-emitting diodes have become more and more advanced and are often used in electric bulletin boards, traffic signals and the like. In such applications, it is necessary to ensure that light is visible from oblique directions as well as from the front. Directionality is reduced by taking measures such as providing multiple diodes facing in respective directions and providing a light diffusing plate or a light diffusing film in the front of a light-emitting diode. Patent document No. 1 proposes a method of reducing directionality by providing a plane on top of a convex lens constituting a light-emitting diode.
It will be noted that proposals have been made recently to use light-emitting diodes for decorative purposes such as tree illumination. A light-emitting diode consumes less power and assures longer life than a light bulb, which is conventionally used for decorative purposes, but is not inherently suitable for decorative purposes due to its sharp directionality. For this reason, a method has been proposed to produce less directional light by forming the surface of the light-transmitting resin of a light-emitting diode to resemble frosted glass (patent document No. 2).
[patent-related document No. 1]
Gazette containing the Utility Model No. 62-73563
[patent-related document No. 2]
JP 2000-58927 A
In decorative applications such as tree illumination, it is often unknown which direction a light-emitting diode faces when installed. It is thus desirable that light can be visible from any directions. In applications like panel illumination (especially when a panel is formed of a metal such as aluminum), the decorative effect of panel illumination is enhanced by allowing light to be reflected by the panel to which the light-emitting diodes are attached as well as by using light directly emitted by light-emitting diodes. Therefore, it is desirable that light radiated from the light-emitting diodes be not only back-to-front directional but also front-to-back, right-to-left and left-to-right directional.
Another point of note is that a large number of light-emitting diodes are used for decorative purposes. In this respect, it is desirable that the fabrication cost be reduced. According to patent document No. 2, an extra lithographic step is required to form the top surface of the light-emitting diode to resemble frosted glass. In such an approach, the fabrication cost is increased.